The present invention concerns a vehicle having an internal combustion engine and a waste heat collecting housing.
It is already known how to utilize the heat contained in the exhaust gas of an internal combustion engine. In this context, refer to German patent documents no. DE 10 2009 032 566 A1, which describes a vehicle with an exhaust gas heat exchanger. An exhaust gas heat exchanger is a heat exchanger with a flow of hot exhaust gas on one side and coolant of an internal combustion engine on the other side. The exhaust gas heat exchanger makes possible a partial “heat recovery,” i.e., a transfer of heat from the hot exhaust gas to the coolant of the internal combustion engine. By use of an exhaust gas heat exchanger, the warm-up phase of the internal combustion engine can be shortened. Many vehicles intended for so-called “cold countries” are outfitted with exhaust gas heat exchangers in order to accomplish some degree of heating support. The drawback of exhaust gas heat exchangers is, among others, that they alter the exhaust gas counterpressure as compared to exhaust gas systems with no exhaust gas heat exchangers and there needs to be a constant “heat pickup,” i.e., the exhaust gas heat exchanger has to be constantly cooled in order to prevent overheating.
The problem which the invention solves is to create a vehicle and a stationary assembly in which the heat given off by an internal combustion engine can be utilized in another manner, i.e., not through an exhaust gas heat exchanger. Moreover, the invention provides a corresponding method for the utilization of part of the heat given off by an internal combustion engine.
Although the invention is described below primarily in connection with a vehicle, it is expressly noted that the invention is not confined to the application in or in connection with vehicles, but can also be employed in “stationary” manner, i.e. in a positionally fixed manner, e.g., in connection with a block-type thermal power station.
The starting point of the invention is a vehicle with an internal combustion engine and an exhaust gas manifold, through which hot exhaust gas coming from the internal combustion engine is introduced into an “engine-side section” of an exhaust gas system. The term “engine-side section” of the exhaust gas system encompasses in particular the section between the exhaust gas manifold and a section of the exhaust gas system adjoining the engine-side section and running in the subfloor region of the vehicle.
The crux of the invention is that a “waste heat collecting housing” which surrounds or encloses at least part of the exhaust gas manifold and/or part of an engine-side section of the exhaust gas system is used to heat the air present in the waste heat collecting housing. The term “waste heat collecting housing” should be interpreted broadly. It is not necessarily confined to a “housing”, but instead should be interpreted quite generally in the sense of an air guiding element.
Thanks to the waste heat collecting housing, at least a part of the exhaust gas manifold and/or a part of an engine-side section of the exhaust gas system is thermally and acoustically “encapsulated”. This dual function (thermal and acoustic encapsulation) is a major benefit of the invention, since the soundproofing expense (e.g., soundproofing of the front wall separating the engine compartment from the passenger compartment) can be decreased in this way.
Preferably, however, the exhaust gas manifold and/or part of an engine-side section of the exhaust gas system are encapsulated as completely as possible by the waste heat collecting housing, since this improves the efficiency of the overall system.
Another benefit of the invention is that it does not require an “intervention” in the exhaust gas system, i.e., the exhaust gas system does not need to be changed.
The heat transfer from the exhaust gas manifold and/or the engine-side section of the exhaust gas system to the air present in the waste heat collecting housing occurs primarily through thermal radiation and convection. Thus, according to the invention, the engine waste heat is utilized directly at the so-called “hot end,” i.e., at the exhaust gas manifold and/or the section of the exhaust gas system near the engine. The “hot end” constitutes the most direct and productive, i.e., most effective “access” to the engine waste heat. With the waste heat collecting housing according to the invention, a systematic encapsulation of the hot end is accomplished. The hot end is the strongest heat radiator in the engine space of a vehicle with internal combustion engine. A direct heat removal from the hot end also has various benefits in terms of the technical operating safety in the engine space.
According to the invention, the air heated in the waste heat collecting housing is utilized                to heat air to be taken into a passenger compartment of the vehicle and/or        to heat cooling fluid of the internal combustion engine and/or        to heat engine oil of the internal combustion engine and/or        to (merely) remove heat from the engine space, wherein in the latter case the heated air coming from the waste heat collecting housing is taken into the surroundings.        
According to one modification of the invention, an air/air heat exchanger is provided by which heat from the air heated in the waste heat collecting housing can be transferred to the air to be taken into a passenger compartment of the vehicle. Thus, the engine waste heat “recovered” via the waste heat collecting housing can be used to heat the air of the passenger compartment. The air/air heat exchanger can be arranged directly in the so-called climate module or climate device of the vehicle, i.e., on the side of the front wall (partition wall between the passenger compartment and the engine space) facing the passenger compartment. By use of such an air/air heat exchanger, a relatively spontaneously responding heating system can be provided or the heating power provided by the cooling system of the internal combustion engine can be enhanced, which is especially advantageous for so-called “cold country vehicles”. Such an air/air heat exchanger as a support for the heating system is also of advantage for modern Diesel vehicles, which put out relatively little heat through the cooling system as compared to vehicles with gasoline engines.
Alternatively or in addition to an air/air heat exchanger, an air/coolant heat exchanger can be provided, by which heat from the air heated in the waste heat collecting housing can be transferred to a coolant of a cooling circuit of the internal combustion engine. By use of such an air/coolant heat exchanger, a transfer of heat from the hot end region of the internal combustion engine to the coolant of the internal combustion engine is possible, which substantially shortens the warm-up phase of the internal combustion engine and has favorable impact on the pollutant emission.
Alternatively or in addition to an air/air heat exchanger or an air/coolant heat exchanger, an air/oil heat exchanger can be provided, by which heat from the air heated in the waste heat collecting housing can be transferred to oil of an oil circuit of the internal combustion engine, i.e., to the engine oil of the internal combustion engine. In this way as well, the warm-up phase of the internal combustion engine can be shortened by recovery of heat from the hot end region.
Since the waste heat collecting housing encloses at least part of the manifold or the entire exhaust manifold and/or part of the engine-side section or a section of the exhaust gas system near the engine, the waste heat collecting housing also works as a muffler. Thus, the hot end region is to a certain extent acoustically encapsulated by the waste heat collecting housing. The thus far customary and necessary soundproofing measures therefore become at least in part obsolete. It is of advantage when the waste heat collecting housing is coated or lined with an appropriately temperature-resistant soundproofing layer.
According to one modification of the invention, at least one catalyst of the exhaust gas system is arranged inside the waste heat collecting housing. The catalyst can be, e.g., a NOx storage catalyst, a SCR (selective catalytic reduction) catalyst, or the like.
Alternatively or in addition to this, it can be provided that an exhaust gas turbocharger or at least a turbine-side region of the exhaust gas turbocharger is arranged inside the waste heat collecting housing.
The engine-side section of the exhaust gas system or a section near the engine is connected to a section of the exhaust gas system running in a subfloor region of the vehicle. The engine-side section or the section of the exhaust gas system near the engine is that section of the exhaust gas system which extends between the exhaust gas manifold and the subfloor region of the vehicle. It can be provided that the waste heat collecting housing extends over the entire length of the engine-side section or the section of the exhaust gas system near the engine. In other words, it can be provided that the waste heat collecting housing extends up to the section of the exhaust gas system running in the subfloor region of the vehicle.
For thermal reasons, it can be provided that the waste heat collecting housing is at least partly made, especially for the most part made, of sheet metal. Alternatively to this, the waste heat collecting housing can also be made from a sufficiently temperature-resistant plastic material.
According to one modification of the invention, the waste heat collecting housing has an air inlet through which air from the surroundings or from an engine space of the vehicle can flow into the waste heat collecting housing. The air located in the engine space, after reaching the operating temperature of the internal combustion engine, is warmer than the surrounding air and after flowing into the waste heat collecting housing from the hot end (i.e., from the exhaust gas manifold and/or the engine-side section of the exhaust gas system or the section near the engine) is further heated.
According to one modification of the invention, the waste heat collecting housing has a first air outlet for heated air. It can be provided that the first air outlet stands in fluidic connection with the air/air heat exchanger and/or the air/coolant heat exchanger and/or the air/oil heat exchanger.
According to one modification of the invention, the waste heat collecting housing has a second air outlet by which air heated in the waste heat collecting housing can bypass the first air outlet and be taken directly (unused) to the surroundings. This makes sense when there is no need to transfer heat via an air/air heat exchanger to the air to be introduced into the passenger compartment or when there is no need to introduce recovered heat into the coolant or the engine oil of the internal combustion engine. Thus, by the second air outlet heat can be removed directly from the engine space (thereby improving the thermal operating safety) without furnishing heat to the coolant or to the engine oil of the internal combustion engine or air to the passenger compartment. The air flowing from the waste heat collecting housing across the second air outlet can be diverted directly downward from the vehicle in the direction of the roadway. The operating mode of “heat removal from engine space” could be the preferred application of the invention for many or most of the operating states of a vehicle.
Moreover, a blower can be provided, which generates an air flow in the waste heat collecting housing directed toward the first and/or the second air outlet. In other words, by use of such a blower air is sucked in through the air inlet of the waste heat collecting housing or air is blown in through the air inlet. As already indicated, the air from the surroundings or from the engine space of the vehicle can be sucked or blown into the waste heat collecting housing. The blower can be arranged inside the waste heat collecting housing. Alternatively, it can also be arranged in the region of the air inlet.
According to one modification of the invention, the air heated in the waste heat collecting housing and taken through the air/air heat exchanger and/or the air/coolant heat exchanger and/or the air/oil heat exchanger and thereby cooled is taken away to the surroundings through an air exhaust duct.
According to one modification of the invention, a valve or gate arrangement controllable by actuators is provided, whereby in dependence on the position of the valve or gate arrangement                the entire air flow coming from the waste heat collecting housing flows away through the first air outlet and the air/air heat exchanger and/or the air/coolant heat exchanger and/or the air/oil heat exchanger, or        the entire heated air flow coming from the waste heat collecting housing bypasses the first air outlet and is diverted (unused) into the surroundings, or        a first partial volume flow of the heated air flow coming from the waste heat collecting housing flows away through the first air outlet and a second partial volume flow of the heated air flow coming from the waste heat collecting housing bypasses the first air outlet and flows away (unused) into the surroundings.        
The actuators and/or the valve or gate arrangement need not be in direct thermal connection with the exhaust gas system, which simplifies the thermal design of the actuators and the valve or gate arrangement.
It makes sense to convey the entire air flow coming from the waste heat collecting housing across the first air outlet when the recovered heat is to be used for heating the passenger compartment air and/or the coolant and/or the engine oil of the internal combustion engine. It makes sense to convey the entire air flow coming from the waste heat collecting housing directly into the surroundings, bypassing the first air outlet, when there is no need to heat the passenger compartment air or the coolant or the engine oil of the internal combustion engine and heat is to be removed from the engine space.
The above-described “mixed mode” (third bullet point) can make sense when both heat needs to be removed from the engine space and the passenger compartment air and/or the coolant of the internal combustion engine and/or the engine oil of the internal combustion engine need to be heated.
According to one modification of the invention, the actuators which control the valve or gate arrangement can have an electrical servo drive.
Moreover, it can be provided that the valve or gate arrangement has a non-activated base position in which the entire air flow coming from the waste heat collecting housing bypasses the first air outlet and is conveyed to the surroundings. For example, the valve or gate arrangement can be biased in the non-activated base position by a spring arrangement. This ensures that the valve or gate arrangement transitions into the non-activated base position upon interference or failure of the actuators.
As already mentioned in the introduction, the subject matter of the invention is not only a vehicle with an internal combustion engine and a waste heat collecting housing, but also a corresponding method for utilizing a portion of the heat given off by an internal combustion engine, wherein the air contained in a waste heat collecting housing is heated by means of the waste heat collecting housing, which encloses at least a portion of an exhaust gas manifold and/or at least a portion of an engine-side section of an exhaust gas system of the internal combustion engine, and the heated air is used directly or indirectly for the heating of air being taken into the passenger compartment of the vehicle.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.